\section{Conclusion}
\label{sec:conclusion}

Our approach could be practical and effective to select
test cases for policy-based software systems interacting not only with XACML policies but also
with policies specified by other policy specification languages (e.g., EPAL).
We make two key contributions in this paper. First, we proposed three test-selection techniques in the context of policy
evolution. 
%To the best of our knowledge, our paper is the first one for automatic test selection in the context of policy
%evolution. 
Second, we conducted experiments to assess the effectiveness and efficiency of our three test-selection
techniques.



%The evaluation results demonstrated that our approach is effective and efficient.


%Among the proposed three test-selection techniques, the evaluation results demonstrated that the technique based recorded
%request evaluation is the most efficient compared with the first two techniques. Besides, we also achieve additional coverage
%of changed policy behaviors with augmented test cases.

%
%generate additional new test cases to cover not-covered-impacted-rules with selected test cases by the preceding techniques.
%
%to select every test case impacted by policy changes.
%
%
%from existing test cases to test program code impacted by policy changes.
%
%comprehensive fault model for ?rewall
%policies, including ?ve types of faults. For each type of
%fault, we present an automatic correction technique. Second, we propose the systematic approach that can automatically correct all or part of the misclassi?ed packets
%of a faulty ?rewall policy. To the best of our knowledge,
%our paper is the ?rst one for automatic correction of ?rewall policy faults. Last, we implemented our approach
%and evaluated its effectiveness on real-life ?rewalls. To
%measure the effectiveness of our approach, we propose
%two metrics, which we believe are general metrics for
%measuring the effectiveness of ?rewall policy correction
%tools. The experimental results demonstrated that our approach is effective to correct a faulty ?rewall policy with
%three types of faults:
%
%Conclusion here!!